Device for monitoring of oil-water interface
A device for monitoring the position of an oil/water contact (OWC, 22) between an oil-continuous fluid (2o) overlying a water-continuous fluid (2w) inside a casing pipe (7), comprising the following features: a transmitter (5) for a generating an electro-magnetic signal (ST), said transmitter (5) provided with electrical energy (GT) from a voltage signal generator (G); said transmitter (5) being arranged inside said oil-continuous fluid (2o) and being above said oil-water contact (22), and being inside said casing pipe (7); said electromagnetic wave signal (ST) for partly propagating downwards from said transmitter (5); said electromagnetic wave signal (ST) for being partly reflected from said oil-water contact (22), and partly reflected by the end of the casing, giving rise to an upward propagating, reflected electro-magnetic signal (SR); a sensor (6) for detecting said reflected electromagnetic signal (SR), said sensor (6) also arranged above said oil-water contact (22), providing a sensor signal (RR) to a receiver (60) for receiving said sensor signal (RR) and further to an analysing device (61) for analysing said sensor signal (RR), e.g. with respect to two-way propagation time or amplitude in order for calculating an elevation level for said oil-water contact (22).
The invention relates to a device for monitoring the position of an oil/water contact (OWC) between an oil-continuous fluid overlying a water-continuous fluid inside a casing pipe, using a transmitter for a generating an electromagnetic signal, and detecting a reflected signal from the oil-water contact.
KNOWN ARTA device for using guided electromagnetic waves along the outside of a conductive casing is presented in U.S. Pat. No. 6,480,000 to Fan-Nian Kong et al.
U.S. Pat. No. 5,926,024 to Blount, “System and method for measuring fluid properties by forming a coaxial transmission line in a cased well”, is a logging instrument which transmits microwave frequency within a section of the wellbore. That apparatus is able to determine which zone is producing excessive amounts of water into the production fluids, but incapable of measuring the distance down to an oil-water contact from a fixed position.
In order to produce a large proportion of oil from a well in which there is a risk of also producing water, there is an advantage in being able to monitor the depth to the oil-water contact (OWC) inside the production zone, inside the casing or screen through the production zone.
The present invention is a solution to this problem, and is represented by a device for monitoring the position of an oil/water contact (OWC) between an oil-continuous fluid overlying a water-continuous fluid inside a casing pipe, comprising the following features:
a transmitter for a generating an electromagnetic signal ST, said transmitter provided with electrical energy from a voltage signal generator;
said transmitter being arranged inside said oil-continuous fluid and being above said oil-water contact, and being inside said casing pipe,
said electromagnetic wave signal for partly propagating downwards from said transmitter;
said electromagnetic wave signal for being partly reflected from said oil-water contact, and partly reflected by the end of the casing, giving rise to an upward propagating, reflected electromagnetic signal;
a sensor for detecting said reflected electromagnetic signal, said sensor also arranged above said oil-water contact, providing a sensor signal to a receiver for receiving said sensor signal and further to an analysing device for analysing said sensor signal, e.g. with respect to two-way propagation time or amplitude in order for calculating an elevation level for said oil-water contact.
Further advantageous features of the invention are given in the dependent claims.
SHORT FIGURE CAPTIONSThe invention is illustrated in the attached drawings, which shall illustrate the invention only, and shall not be construed as a limitation of the invention, which shall be defined by the claims attached.
Similar to the embodiment of
Below is given a description of preferred embodiments of the invention.
All preferred embodiments of the invention comprise the following features:
A transmitter 5 for a generating an electromagnetic signal ST, is arranged inside the casing pipe 7. The transmitter 5 is provided with electrical energy signals GT from a voltage signal generator G, see upper right part of
The electromagnetic wave signal ST will partly propagate downwards from the transmitter 5. The transmitter may have several different embodiments as will be described below. Further, while the signal will be attenuated while propagating downward through the oil and/or water, part of the electromagnetic wave signal ST will be partly reflected from the oil-water contact 22, and also partly reflected by the end of the casing, giving rise to an upward propagating, reflected electromagnetic signal SR.
A sensor 6 is arranged for detecting said reflected electromagnetic signal SR. The sensor 6 is also arranged above the oil-water contact 22, providing a sensor signal RR which it provides to a receiver 60 for receiving the sensor signal RR. The receiver is further connected to an analysing device 61 for analysing the sensor signal RR, e.g. with respect to two-way propagation time or amplitude in order for calculating an elevation level for the oil-water contact 22.
The Casing and Tubing in the Production Zone
The casing pipe 7 has an annulus room 8 around the central production pipe 70, as illustrated in
In the preferred embodiment illustrated in
In the preferred embodiment illustrated in
In the preferred embodiments of the invention, the electromagnetic transmitter 5 is arranged inside an upper portion 8u of said annulus room. However, there is a possibility that if the packer 4 arranged to seal of the upper part of the annulus room 8u is not conductive, for instance made in rubber or similar material, the transmitter 5 may be arranged above the packer 4. In all the illustrated embodiments of the invention, the electromagnetic transmitter 5 is arranged below or above the mentioned packer 4 between the inside of the casing pipe 7 and the outside of the conductive tubing string 70. The packer 4 forms an upward barrier for fluids in the annulus room 8. In an advantageous embodiment of the invention, the above-mentioned toroidal antenna 50 is provided with a ring core 51 of mu-metal or ferrite, having high permeability.
In the preferred embodiments of the invention the emitted electromagnetic signal ST has a frequency or frequencies in the range between 1 kHz and 10 MHz. More specific frequencies of 100 kHz and 1 MHz have been used in the modelling as described below. The modelled signal follows a Ricker pulse having a centre frequency of 100 kHz or 1 MHz, respectively. The power supplied by the generator G is in the range between 1 W and 10 kW.
In a preferred embodiment as illustrated in FIGS. 1 to 6, the sensor 6 provides said received electromagnetic signal RR to said receiver 60. An analysing device 61 receives the signal from the receiver 60 via a signal conductor 62 arranged having a passage through the packer 4, when the sensor and/or the receiver is arranged below the packer 4, which is the normal case.
Wire Waveguide Along Casing Wall
In a preferred embodiment of the invention, wire or rod 51 may be coated by an electrical insulation material, but this is not absolutely necessary as long as the wire 51 has a separation from the casing 7.
Wire Waveguide Along Central Pipe's Outer Wall
Wire Helix Along Central Pipe's Outer Wall
Simplified Device in Openhole
In fact, in a simplified embodiment (not illustrated) of the invention, the model illustrated in
Model Parameters
In our modelling, we have used a conservative estimate for the resistivity of crude oil ρoil=100 Ωm. Probably this number is a low estimate, and would be higher in nature. We have used a resistivity of water or brine ρw=0.5 Ωm. The transmitter 5 is arranged 5 metres from the upper end of the annulus room 8u, and in one of our mathematically modelled examples, the oil-water contact 22, OWC is 100 metres below the transmitter 5, i.e. 105 metres below the packer 4, and 25 metres above the lower end of the annulus room 8 I. A pulse signal ST of pulse width 10 μs is emitted. The two-way propagation time will thus be about 40 μs, giving the reflected pulse signal SR good temporal separation from the transmitted pulse signal ST. Pulse signal frequencies of 100 kHz and 1 MHz are used in the models. For the 100 kHz signal, the attenuation of the maximum amplitude of the pulse is 0.4 dB/m in the oil for the Hz-component, (see
Field Direction Definitions
The field model shown in
In case of using long wavelengths or in case of an undifferentiated oil/water mixture in large proportions of the annulus room 8, giving problems in defining an oil-water contact 22, the reflection from the lower end of the casing (as indicated in
Claims
1-32. (canceled)
33. A device for monitoring the position of an oil/water contact (OWC, 22) between an oil-continuous fluid (20) overlying a water-continuous fluid (2w) inside a casing pipe (7) in a production well, comprising the following features:
- a transmitter (5) and a sensor (6), said transmitter for generating an electromagnetic signal (ST), said transmitter (5) provided with electrical energy (GT) from a voltage signal generator (G);
- said transmitter (5) and said sensor (6) for being arranged inside said oil-continuous fluid (2o) and for being located above said oil-water contact (22) and inside said casing pipe (7),
- said electromagnetic wave signal (ST) for partly propagating downwards from said transmitter (5); said electromagnetic wave signal (ST) for being partly reflected from said oil-water contact (22), and partly reflected by the end of the casing, giving rise to an upward propagating, reflected electro-magnetic signal (SR);
- said sensor (6) for detecting said reflected electromagnetic signal (SR), providing a sensor signal (RR) to
- a receiver (60) for receiving said sensor signal (RR) and forwarding said sensor signal (RR) to an analyzing device (61) for analyzing said sensor signal (RR), e.g. with respect to two-way propagation time or amplitude in order for calculating an elevation level for said oil-water contact (22).
34. A device according to claim 33, said transmitter (5) also being arranged in an annulus room (8) between an outside of an inner, conductive tubing string (70) arranged inside said casing pipe (7), and the inner side of said casing pipe (7), in which said conductive tubing string (70) constitutes a waveguide for at least part of the two-way path of said EM signals (ST, SR).
35. A device according to claim 34, in which said transmitter (5) comprises a toroidal transmitter antenna (50), said antenna (50) being arranged with the toroid around the circumference of said conductive tubing string (70), said toroidal antenna (50) for generating a transverse magnetic field (HTM) with respect to said conductive tubing string (70).
36. A device according to claim 33, said transmitter (5) for generating a transverse electric field (ETE) between an outward facing side of an inner, conductive wire or rod (51) arranged inside said casing pipe (7), and close to, but not in metallic electric contact with, the inner side of, said casing pipe (7), in which said conductive wire or rod (51) constitutes a waveguide for a main portion of the transmitted EM energy of said transverse electric field (ETE) along at least part of the two-way path for said EM signals (ST, SR) along said conductive wire or rod (51).
37. A device according to claim 36, in which said wire or rod (51) being arranged along a helicoidal path (52) along said inner wall of said casing pipe (7) and extending between said transmitter (5) and at least down to said oil-water contact (22, OWC), for extending said two-way path for said EM signals (ST, SR) along said helicoidal path (52) of said conducting wire (51), in order for better resolution and general improved response in measuring the position of said oil-water contact (22, OWC) along said conducting wire (51).
38. A device according to claim 36, in which said wire or rod (51) is coated by an electrical insulation material.
39. The device of claim 33, said transmitter (5) for generating an electromagnetic field between a conductive wire or rod (53) arranged outside, of close to but not in metallic electric contact with, said central pipe (70), and inside relative to the inner surface of said casing pipe (70), in which said conductive wire (52) constitutes a waveguide for a main portion of the transmitted EM energy along at least part of the two-way path for said EM signals (ST, SR), said conductive insulated wire (52) for generating a transverse electric field (ETE) with respect to said wire (52).
40. A device according to claim 39, in which said wire (53) being arranged along a helicoidal path (54) along said outer wall of said tubing pipe (70) and extending between said transmitter (5) and at least down to said oil-water contact (22, OWC), for extending said two-way path for said EM signals (ST, SR) along said helicoidal path (54) of said insulated wire (53), in order for better resolution of measuring the distance of said oil-water contact (22, OWC) along said wire (51).
41. A device according to claim 34, in which said conductive tubing string (70) extends at least between said transmitter (5) and said oil-water contact (OWC, 22).
42. A device according to claim 33, in which said electromagnetic transmitter (5) is arranged inside an upper portion (8u) of said annulus room.
43. A device according to claim 33, in which said electromagnetic transmitter (5) is arranged below or above a packer (4) between said inside of said casing pipe (7) and said outside of said conductive tubing string (70), said packer (4) forming an upwards barrier for fluids in said annulus room (8).
44. A device according to claim 35, in which said toroidal antenna (50) is provided with a ring core (51) having high permeability.
45. A device according to claim 33, in which said electromagnetic signal (ST) has a frequency or frequencies in the range between 1 kHz and 10 MHz.
46. A device according to claim 45, in which said electromagnetic signal (ST) has a frequency or frequencies in the range between 100 kHz and 1 MHz.
47. A device according to claim 33, in which the power supplied by said generator (G) being in the range between 1 W and 10 kW.
48. A device according to claim 33, in which said sensor (6) provides said received electromagnetic signal (RR) to said receiver (60) and said analysing device (61) via a signal conductor (62) arranged having a passage through a packer (4), with the sensor and/or the receiver being arranged below said packer (4).
49. A device according to claim 33, having said wire or rod (53, 54) arranged along a central production pipe (70) for use with said exterior casing pipe (7) replaced by a metallic screen or mesh (72) through a production zone.
50. A method for monitoring the position of an oil/water contact (OWC, 22) between an oil-continuous fluid (20) overlying a water-continuous fluid (2w) inside a production casing pipe (7), comprising the following steps:
- arranging a transmitter (5) and a sensor (6) inside said casing pipe (7), in said oil-continuous fluid (20) and above said oil-water contact (22), and generating an electromagnetic signal (ST), said transmitter (5) provided with electrical energy (GT) from a voltage signal generator (G);
- said electromagnetic wave signal (ST) partly propagating downwards from said transmitter (5); and partly reflecting from said oil-water contact (22), giving rise to an upward propagating, reflected electromagnetic signal (SR);
- said sensor (6) detecting said reflected electromagnetic signal (SR) and providing a sensor signal (RR) to a receiver (60) and forwarding said sensor signal (RR) to an analysing device (61) for analysing said sensor signal (RR), e.g. with respect to two-way propagation time or amplitude, calculating an elevation level for said oil-water contact (22).
51. The method of claim 50, arranging said transmitter (5) in an annulus room (8) between an outside of an inner, conductive tubing string (70) inside said casing pipe (7), and the inner side of said casing pipe (7), using said conductive tubing string (70) as a waveguide for at least part of the two-way path of said EM signals (ST, SR).
52. The method according to claim 50, in which said transmitter (5) uses a toroidal transmitter antenna (50), and arranging said antenna (50) with the toroid around the circumference of said conductive tubing string (70), said toroidal antenna (50) generating a transverse magnetic field (HTM) with respect to said conductive tubing string (70).
53. The method according to claim 50, said transmitter (5) generating a transverse electric field (ETE) between an outward facing side of an inner, conductive wire or rod (51) arranged inside said casing pipe (7), and close to, but not in metallic electric contact with, the inner side of, said casing pipe (7), in which said conductive wire or rod (51) constitutes a waveguide for a main portion of the transmitted EM energy of said transverse electric field (ETE) along at least part of the two-way path for said EM signals (ST, SR) along said conductive wire or rod (51).
54. The method according to claim 50, in which said wire or rod (51) is arranged along a helicoidal path (52) along said inner wall of said casing pipe (7) and extending between said transmitter (5) and at least down to said oil-water contact (22, OWC), for extending said two-way path for said EM signals (ST, SR) along said helicoidal path (52) of said conducting wire (51), in order for better resolution and general improved response in measuring the position of said oil-water contact (22, OWC) along said conducting wire (51).
55. The method according to claim 50, coating said wire or rod (51) using an electrical insulation material.
56. The method of claim 50, using said transmitter (5) for generating an electromagnetic field between a conductive wire or rod (53) arranged outside, of close to but not in metallic electric contact with, said central pipe (70), and inside relative to the inner surface of said casing pipe (70), in which said conductive wire (52) is used as a waveguide for a main portion of the transmitted EM energy along at least part of the two-way path for said EM signals (ST, SR), said conductive insulated wire (52) generating a transverse electric field (ETE) with respect to said wire (52).
57. The method according to claim 56, in which said wire (53) is arranged along a helicoidal path (54) along said outer wall of said tubing pipe (70) and extending between said transmitter (5) and at least down to said oil-water contact (22, OWC), for extending said two-way path for said EM signals (ST, SR) along said helicoidal path (54) of said insulated wire (53), in order for better resolution of measuring the distance of said oil-water contact (22, OWC) along said wire (51).
58. The method according to claim 51, in which said conductive tubing string (70) extends at least between said transmitter (5) and said oil-water contact (OWC, 22).
59. The method according to claim 50, in which said electromagnetic transmitter (5) is arranged inside an upper portion (8u) of said annulus room.
60. The method according to claim 50, in which said electromagnetic transmitter (5) is arranged below or above a packer (4) between said inside of said casing pipe (7) and said outside of said conductive tubing string (70), said packer (4) forming an upwards barrier for fluids in said annulus room (8).
61. The method according to claim 53, in which said toroidal antenna (50) is provided with a ring core (51) having high permeability.
62. The method according to claim 50, in which said electromagnetic signal (ST) transmits a signal with a frequency or frequencies in the range between 1 kHz and 10 MHz.
63. The method according to claim 62, in which said transmitted electromagnetic signal (ST) has a frequency or frequencies in the range between 100 kHz and 1 MHz.
64. The method according to claim 50, in which the power supplied by said generator (G) being in the range between 1 W and 10 kW.
Type: Application
Filed: Mar 19, 2004
Publication Date: Feb 22, 2007
Patent Grant number: 7453265
Inventors: Svein Johnstad (Bones), Fan-Nian Kong (Oslo), Harald Westerdahl (Dal)
Application Number: 10/549,172
International Classification: G01V 3/18 (20060101);